The invention pertains to cytometry and particularly to portable cytometry. More particularly, the invention pertains to blood analysis.
HIV and malaria are two of the leading causes of mortality and morbidity, each of which is preventable with prompt diagnosis and effective treatment. The overwhelming global burden of both of these diseases occurs in Sub-Saharan Africa. There is evidence to suggest that the prevalence of malaria parasitaemia increases with HIV infection, the incidence of malaria increases with HIV infection, HIV increases the risk that a malaria patient will develop severe malaria, and malaria prophylaxis or treatment may be less effective with HIV co-infection. For HIV monitoring, a marker of interest is CD4+ lymphocytes. CD4 depletion appears to be directly linked with the pathogenesis of HIV disease.
One may note that any variation in the total white blood cell count or lymphocyte count could affect a person's CD4 count. This is a reason why some people may prefer to talk about the CD4 percentage which is less variable.
When ordering a complete blood count (CBC), one may get a hematocrit and hemoglobin (which tell provide information about red blood cells) and a white blood cell count. A “differential” may indicate the different types of white blood cells and what percentage are neutrophils, lymphocytes, monocytes, eosinophils, basophils, and so forth. With HIV, the interest is in the lymphocytes.
The T-cell count (CD3 count) may include the CD4 count and the CD8 count. The CD4/CD8 ratio might not used often anymore. Higher numbers appear best for these measures, but one may avoid some confusion by paying attention to the viral load, the absolute count CD4 count, and the CD4 percentage and ignore the CD4/CD8 ratio.
CD4+ (also called T-helper) lymphocytes may be responsible for the immunological defense of the body. Their loss due to HIV infection may result in a progressive deterioration of the immune system and progression to symptoms associated with acquired immune deficiency syndrome (AIDS). Treatment guidelines may call for the use of quantitative CD4+ lymphocyte and HIV viral load tests to determine when anti-retroviral drug treatment should be started, to assess how well a treatment regimen is working, and to assist in determining whether a switch to an alternative drug regimen is needed.
There are ever increasing numbers of HIV-positive individuals in developing countries who will continue to overburden and overwhelm health care services. Existing facilities to monitor CD4+ lymphocyte counts in HIV-positive individuals are either limited or absent in most developing countries because the existing test methods are too expensive and complex. The availability of a simple, inexpensive, semi-quantitative approach for monitoring CD4+ lymphocytes could result in the following disease and public health impact. A simplified, low cost easy-to-use device for testing and monitoring CD4+ lymphocyte levels may enable CD4 testing to be used more commonly and consistently, increasing the effectiveness of HIV therapies and decreasing drug resistance, could be very valuable in the developing world.
Early and accurate diagnosis of infection due to malaria is important for effective disease management and to prevent progression and development of complications such as cerebral malaria. The two most virulent and common species of malaria are plasmodium (P) falciparum and plasmodium vivax, and hence the identification of these two species via a low-cost, easy-to-use device could be very valuable in the developing world.
U.S. Provisional Patent Application 60/753,293 filed Dec. 22, 2005, is hereby incorporated by reference. U.S. Provisional Patent Application 60/755,014 filed Dec. 29, 2005, is hereby incorporated by reference. U.S. patent application Ser. No. 10/908,460, filed May 12, 2005, is hereby incorporated by reference. U.S. patent application Ser. No. 10/908,461, filed May 12, 2005, is hereby incorporated by reference. U.S. patent application Ser. No. 11/306,508, filed Dec. 30, 2005, is hereby incorporated by reference. A continuation-in-part of U.S. patent application Ser. No. 10/950,898, filed Sep. 27, 2004, is hereby incorporated by reference. U.S. patent application Ser. No. 10/938,265, filed Sep. 9, 2004, is hereby incorporated by reference.